An ambitious project to catalogue every habitable planet has discovered seven worlds inside the Milky Way that could possibly harbour life.

Marking its first anniversary, the Habitable Exoplanets Catalog said it had far exceeded its expectation of adding one or two new planets this year in its search for a new earth.

In recent years scientists from the Puerto Rico-based Planetary Habitability Laboratory that runs the catalogue have sharpened their techniques for finding new planets outside our solar system.

Chile’s High Accuracy Radial Veolocity Planet Searcher and the orbiting Kepler Space Telescope are two of the many tools that have increased the pace of discoveries.

The Planetary Habitability Laboratory launched the Habitable Exoplanets Catalog last year to measure the suitability for life of these emerging worlds and as a way to organise them for the public.

It has found nearly 80 confirmed exoplanets with a similar size to Earth but only a few of those have the right distance from their star to support liquid surface water - the presence of which is considered essential to sustain life.

Seven potentially habitable exoplanets are now listed by the Habitable Exoplanets Catalog, including the disputed Gliese 581g, plus some 27 more from NASA Kepler candidates waiting for confirmation.

Although all these exoplanets are superterrans are considered potentially habitable, scientists have not yet found a true Earth analogue.

Over the next year, the Habitable Exoplanets Catalog will go further in its analysis of the planets that could possibly harbour life, offering new visualisations and habitability assessments.

However, the team says the biggest impact over the next 12 months will come from new discoveries rather than deeper analysis of planets it has already found.

A spokesperson said: “A true Earth analogue or a potentially habitable exomoon would be big discoveries.”

“Certainly, this was the right time to start mapping the habitable universe around us.”